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1 | /* Copyright (C) 1993-2025 Free Software Foundation, Inc. | |
2 | This file is part of the GNU C Library. | |
3 | ||
4 | The GNU C Library is free software; you can redistribute it and/or | |
5 | modify it under the terms of the GNU Lesser General Public | |
6 | License as published by the Free Software Foundation; either | |
7 | version 2.1 of the License, or (at your option) any later version. | |
8 | ||
9 | The GNU C Library is distributed in the hope that it will be useful, | |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
12 | Lesser General Public License for more details. | |
13 | ||
14 | You should have received a copy of the GNU Lesser General Public | |
15 | License along with the GNU C Library; if not, see | |
16 | <https://www.gnu.org/licenses/>. | |
17 | ||
18 | As a special exception, if you link the code in this file with | |
19 | files compiled with a GNU compiler to produce an executable, | |
20 | that does not cause the resulting executable to be covered by | |
21 | the GNU Lesser General Public License. This exception does not | |
22 | however invalidate any other reasons why the executable file | |
23 | might be covered by the GNU Lesser General Public License. | |
24 | This exception applies to code released by its copyright holders | |
25 | in files containing the exception. */ | |
26 | ||
27 | #include "libioP.h" | |
28 | #include <stdio.h> | |
29 | ||
30 | char * | |
31 | _IO_fgets (char *buf, int n, FILE *fp) | |
32 | { | |
33 | size_t count; | |
34 | char *result; | |
35 | int old_error; | |
36 | CHECK_FILE (fp, NULL); | |
37 | if (n <= 0) | |
38 | return NULL; | |
39 | if (__glibc_unlikely (n == 1)) | |
40 | { | |
41 | /* Another irregular case: since we have to store a NUL byte and | |
42 | there is only room for exactly one byte, we don't have to | |
43 | read anything. */ | |
44 | buf[0] = '\0'; | |
45 | return buf; | |
46 | } | |
47 | _IO_acquire_lock (fp); | |
48 | /* This is very tricky since a file descriptor may be in the | |
49 | non-blocking mode. The error flag doesn't mean much in this | |
50 | case. We return an error only when there is a new error. */ | |
51 | old_error = fp->_flags & _IO_ERR_SEEN; | |
52 | fp->_flags &= ~_IO_ERR_SEEN; | |
53 | count = _IO_getline (fp, buf, n - 1, '\n', 1); | |
54 | /* If we read in some bytes and errno is EAGAIN, that error will | |
55 | be reported for next read. */ | |
56 | if (count == 0 || ((fp->_flags & _IO_ERR_SEEN) && errno != EAGAIN)) | |
57 | result = NULL; | |
58 | else | |
59 | { | |
60 | buf[count] = '\0'; | |
61 | result = buf; | |
62 | } | |
63 | fp->_flags |= old_error; | |
64 | _IO_release_lock (fp); | |
65 | return result; | |
66 | } | |
67 | ||
68 | weak_alias (_IO_fgets, fgets) | |
69 | ||
70 | # ifndef _IO_MTSAFE_IO | |
71 | strong_alias (_IO_fgets, __fgets_unlocked) | |
72 | libc_hidden_def (__fgets_unlocked) | |
73 | weak_alias (_IO_fgets, fgets_unlocked) | |
74 | libc_hidden_weak (fgets_unlocked) | |
75 | # endif |